1. Field of the Invention
The present invention relates to a portable automatic syringe device enabling an injection of liquid medicine for a prolonged time and an injection needle unit thereof, and more particularly to a portable automatic syringe device having a configuration including a separable rotating shaft adapted to provide a drive force to a piston included in the automatic syringe device so that the rotating shaft can be separated, along with the piston, from a housing of the syringe device upon re-filling a syringe of the syringe device with a liquid medicine, and set in position in the housing after the refilling of the liquid medicine. The present invention also relates to an injection needle unit including an injection needle member provided with a curved portion capable of absorbing impact. The present invention further relates to an injection needle unit including an injection needle member provided with a glucose sensor, and a portable automatic syringe device using the injection needle member.
2. Description of the Prior Art
Automatic syringe devices, which enable an injection of liquid medicine for a prolonged time, are well known. Typically, known automatic syringe devices have a configuration in which a push means for pushing a syringe piston is coupled to a housing receiving an injection syringe. For example, such automatic syringe devices are disclosed in Japanese Utility Model Laid-open Publication No. Sho. 52-3292 and U.S. Pat. No. 4,417,889. The syringe device disclosed in Japanese Utility Model Laid-open Publication No. Sho. 52-3292 has inconvenience in carrying it because it has an injector mounted outside a basic case, thereby requiring a double case structure. In order to solve such a disadvantage, an automatic syringe device requiring no double case structure has been proposed, as in the above mentioned U.S. Pat. No. 4,417,889. FIGS. 1 and 2 illustrate a control circuit and a structure of the automatic syringe device disclosed in U.S. Pat. No. 4,417,889, respectively. Referring to FIG. 1, the output of an oscillator A1 is coupled to a timer A2 which is, in turn, coupled at its output to a digital comparator A3. The digital comparator A3 also receives an output from a fixed number switch A4. The output of the digital comparator A3 is connected to a counter A6 and an R/S flip-flop A9. Another oscillator A5 is also provided which has an output coupled to counters A6 and A13, and AND gates A10 and A11. The flip-flop A9 is reset by an output from a digital comparator A7. Another R/S flip-flop A16 is also provided which is reset by an output from a digital comparator A14 coupled to the counter A13. A control unit A17 is also coupled to the counter A13. The control unit A17 serves to activate the counter A13 in accordance with an operation of a manual infusion switch A12. The control unit A17 applies its output to the counters A13 and A16. The output from the control unit A17 is also sent to a counter A21. The output of the counter A21 is coupled to a digital comparator A22 which is, in turn, coupled to a step motor driver A19 for driving a step motor A20. The output of the flip-flop A16 is coupled to one input of the AND gate A11, which is also coupled at the other input thereof to the oscillator A5. The output of the AND gate A11 is coupled to one input of an OR gate A18. Fixed number switches A15 and A25 are connected to the digital comparators A14 and A22, respectively. Each of the fixed number switches A4, A8, A15, and A25 has five protruding insert bars and serves to provide a reference value for an associated one of the digital comparators A3, A7, A14, and A22. A light source A24 and a photo sensor A23 are coupled to the counter A21 in order to provide sensing results thereof to the counter A21, respectively. Referring to FIGS. 2 and 3, the arrangements of the light source A24 and photo sensor A23 are illustrated. As shown in FIGS. 2 and 3, the light source A24 and photo sensor are arranged in such a fashion that they face each other while being vertically spaced from each other. A gear plate, which is included in a gear mechanism G, is interposed between the light source A24 and photo sensor A23. The gear plate has a plurality of through holes A26 uniformly spaced from one another in a circumferential direction, as shown in FIG. 3. The gear plate is fixedly fitted around a gear shaft A27 having a screw portion. A piston plate A28 is threadedly coupled to the gear shaft A27 in the form of a nut in such a fashion that it slides along the screw portion of the gear shaft A27 when the gear shaft A27 rotates. The rotation of the gear shaft A27 is carried out by a drive force from the motor A20 transmitted via the gear mechanism G. The driving of the motor A20 is controlled by the operations of the counter A21, digital comparator A22, switch A25, and motor drive A19. All the above mentioned elements of the syringe device are received in a housing. In particular, the light source A24 and photo sensor A23 are fixedly mounted at an upper portion of the housing by means of a bracket fixed to the housing. In this syringe device, a liquid medicine, such as insulin, contained in a syringe I is outwardly injected through an injection needle N connected to the syringe I, by a slide movement of the piston plate A28. In such a syringe device, however, the housing and syringe I thereof are exposed to ambient air. As a result, moisture and water are likely to penetrate into the syringe device. For this reason, there is inconvenience in that if the user desires to take a shower while the syringe is in place, then the housing should be contained in a separate sealing case.
In order to solve such a problem, a sealable syringe device has been proposed by the applicant. Such a sealable syringe device is illustrated in FIG. 4 which is a front view. Referring to FIG. 4, the syringe device includes a cover 10 sealably coupled to the upper end of a housing 20, and a bottom cover 40 sealably coupled to the lower end of the housing 20. A connector 2, to which a feeding tube is integrally connected, is threadedly coupled to the cover 10. The connector 2 communicates with a syringe 21 received in the housing 10. A piston 22 is slidably fitted in the syringe 21. A liquid medicine to be syringed is contained in the syringe 21. A power transmission means 30 is mounted on the bottom surface of the housing 20. The power transmission means 30 has a rotating shaft 31 to which a disc type push means 50 is threadedly coupled. The disc type push means 50 moves vertically by a rotation of the rotating shaft 31, thereby vertically moving the piston 22.
Referring to FIG. 5, which is a plan view of FIG. 4, the cover 10, to which the connector 2 connected with the feeding tube 1 is connected, is arranged on the left portion of the upper surface of the housing 20. A battery cover 24 is arranged on the right portion of the upper surface of the housing 20.
FIG. 6 is a cross-sectional view taken along the line A--A of FIG. 5. As shown in FIG. 6, the cover 10 is centrally provided with a threaded hole 11 in which the connector 2 is threadedly fitted at its lower end. The cover 10 is also provided at its lower end with a bolt portion 12 threadedly fitted in the upper end of the housing 20. A packing 13 is fitted around the bolt portion 12 of the cover 10 between the lower end of the cover 10 and the upper end of the housing 20. A syringe receiving chamber 23 is defined in the interior of the housing 20. The push means 50 is fitted in the lower end of the housing 20 in such a fashion that it slides vertically in the housing 20. The housing 20 is also formed at its inner surface with a vertical push means guide groove 25 adapted to guide a vertical movement of the push means 50 and vertical piston guide grooves 27 adapted to guide a vertical movement of the piston 22.
FIG. 7 shows a detailed configuration of the push means 50 threadedly coupled to the rotating shaft 31 of the power transmission means 30, along with a detailed configuration of the power transmission means 30. As shown in FIG. 7, the push means 50 includes a lower disc 54 threadedly coupled to the rotating shaft 31 in such a fashion that it slides vertically along the rotating shaft 31. The lower disc 54 is provided at its periphery with a guide protrusion 51 engaged in the guide groove 25 of the housing 20 and adapted to guide the vertical movement of the lower disc 54. The push means 50 also includes an upper disc 55 integrally formed with the lower disc 54. The upper disc 55 is provided at its periphery with an engagement means 52. The upper disc 55 is fitted in a sleeve plate 26 fixed to the lower end of the piston 22 in such a manner that its engagement means 52 engages with a mating engagement means formed on the inner peripheral surface of the sleeve plate 26. The sleeve plate 26 is also provided at its outer peripheral surface with protrusions engaging with the guide grooves 27 respectively. The power transmission means 30 includes a reduction mechanism 33 for transmitting the rotating force of a motor (not shown) to the rotating shaft 31 in a speed-reduced manner.
In order to use the syringe device having the above mentioned configuration, the piston 22, which is in a state separated from the housing 20, is first fitted in the syringe 21 which is also in a state separated from the housing 20, in such a manner that it is completely inserted into the syringe 21. In this state, a disposable injection needle (not shown) is fitted onto the tip 21-1 of the syringe 21. Thereafter, the injection needle is penetrated into the interior of a phial through the plug of the phial. In this state, the piston 22 is pulled to suck a liquid medicine (for example, insulin) contained in the phial into the syringe 21.
The piston 22, which is in a state fitted in the syringe 21 containing the liquid medicine, is then inserted into the syringe receiving chamber 23 of the housing 20 in such a manner that it is seated on the push means 50. Subsequently, the cover 10 is threadedly coupled to the upper end of the housing 23. The connector 2 is then threadedly fastened to the cover 10. As the connector 2 is threadedly fastened to the cover 10, it is fitted onto the syringe tip 21-1. Thus, the syringe 21 is maintained in a sealed state in the housing 20. When the motor (not shown) drives under the above condition, the push means 50 moves upwardly, thereby upwardly pushing the piston 22. As a result, the liquid medicine contained in the syringe 21 is outwardly injected from the syringe 21. At this time, the upward movement of the push means 50 is accurately carried out because its guide protrusion 51 engages with the guide groove 25. Since the engagement means 52 of the push means 50 engages with the mating engagement means of the sleeve plate 26 integrally formed with the lower end of the piston 22, the upward movement of the piston 22 is also accurately carried out.
In such a syringe device, it is necessary to set the initial height or vertical position of the lower disc 54 of the push means 50 every time the syringe 21 filled with a liquid medicine is inserted into the housing 20, in order to allow the piston 22 to be accurately seated on the upper disc 55 of the push means 50. However, it is difficult to accurately set a desired initial vertical position of the lower disc 54.
Meanwhile, FIG. 9 illustrates an example of a conventional injection needle unit used for portable automatic syringe devices enabling a prolonged injection of a liquid medicine. As shown in FIG. 9, the injection needle unit includes a feeding tube 1, a "-" shaped straight injection needle member (called a "straight butterfly-shaped injection needle") 3 connected to one end of the feeding tube 1, and a connector 2 connected to the other end of the feeding tube 1.
In order to use such an injection needle unit, the user himself slantly penetrates the injection needle member 3 into the subcutaneous tissue while observing the penetration of the injection needle member 3 with the naked eye. The reason why the user observes the penetration of the injection needle member 3 with the naked eye is because the injection needle member 3 has a straight shape. However, such an observation is very uncomfortable.
Furthermore, when the straight butterfly-shaped injection needle member 3 penetrates the subcutaneous tissue of the user on a slanted angle, its tip may be easily blocked by the subcutaneous tissue because the subcutaneous tissue is a multilayer tissue. As a result, the above mentioned conventional injection needle unit has a drawback in that it is difficult to smoothly inject the liquid medicine, namely, insulin.
The straight butterfly-shaped injection needle member 3 is also likely to move in the subcutaneous tissue of the user because it penetrates the subcutaneous tissue of the user on a slanted angle. In this case, the subcutaneous tissue may be damaged. In severe cases, blood may flow out of the subcutaneous tissue. The user may also feel a severe pain.
As mentioned above, the conventional injection needle unit has a drawback in that it is difficult to smoothly inject insulin because the injection needle member 3, which penetrates the subcutaneous tissue of the user on a slanted angle, may be easily blocked at its tip by the subcutaneous tissue. To this end, the feeding tube of such a conventional injection needle unit inevitably has an increased diameter. However, such a feeding tube having an increased diameter results in a possibility of an excessive insulin injection. In addition, this may result in wastage of expensive insulin. For instance, where it is desired to inject insulin into the user using an automatic syringe device equipped with the above mentioned injection needle unit, it is necessary to completely vent air existing in the feeding tube 1 and injection needle member 3 before penetrating the injection needle member 3 into the subcutaneous tissue of the user. To this end, insulin, which is contained in the syringe device, is outwardly discharged through the feeding tube 1 and injection needle member 3, thereby venting air. In this case, a large amount of insulin is wasted where the conventional injection needle unit having the diameter-increased feeding tube is used.
The use of such a diameter-increased feeding tube also results in an increase in the manufacturing costs.
In the case of the injection needle unit illustrated in FIG. 9, its connector 2 is simply fitted onto a connector portion 20-5 of the syringe device housing 20. For this reason, the connector 2 may be incidentally separated from the connector portion 20-5 of the housing 20.
In order to solve this problem, an injection needle unit has been proposed which has a configuration capable of preventing a separation of its connector. Such an injection needle unit is illustrated in FIGS. 10 and 11, respectively.
As shown in FIGS. 10 and 11, the injection needle unit includes a feeding tube 1, an injection needle member 3 connected to one end of the feeding tube 1, and a connector 2 connected to the other end of the feeding tube 1.
In the case of the injection needle unit shown in FIGS. 10 and 11, the injection needle member 3 has an "L" shaped injection needle 3-11. This injection needle 3-11 has a first portion, namely, a horizontal portion, fitted in a connecting rib 3-12 integrally formed with one end of the feeding tube 1, and a second portion, namely, a vertical portion, provided with a needle tip. The injection needle 3-11 is provided with a curved portion 3-13 at its horizontal portion fitted in the connecting rib 3-12, as shown in FIG. 11. A depressing member 3-14 is integrally formed with the connecting rib 3-12 in such a fashion that the injection needle 3-11 protrudes perpendicularly from the depressing member 3-14. The depressing member 3-14 is depressed against the skin of the user upon penetrating the injection needle member 3 into the subcutaneous tissue. A bacterial infection prevention member 3-14-1, which is made of a disinfected nonwoven fabric, is attached to the surface of the depressing member 3-14 which comes into contact with the skin of the user upon penetrating the injection needle unit 3 into the subcutaneous tissue. The feeding tube 1 of FIGS. 10 and 11 has a reduced diameter and an increased length, as compared to that of FIG. 9. The connector 2, which is connected to the other end of the feeding tube 1, has a male thread 2-15. The connector 2 is protected by a protection cap 2-17 which has a female thread 2-16 threadedly coupled to the male thread 2-15 of the connector 2. In use, the connector 2 is threadedly coupled to a connector portion 20-5 of a housing 20 included in an automatic insulin syringe device. The connector portion 20-5 of the housing 20 has a female thread 20-5a threadedly coupled to the male thread 2-15 of the connector 2. In FIG. 10, the reference numeral "3-18" denotes a needle protection cap.
Where it is desired to inject insulin contained in the automatic insulin syringe device using the above mentioned injection needle unit, the protection cap 2-17 is first separated from the connector 2, which is, in turn, threadedly coupled to the connector portion 20-5 of the housing 20. Thereafter, the needle protection cap 3-18 is separated from the injection needle 3-11. The user then penetrates the injection needle 3-11 into the subcutaneous tissue while depressing the depressing member 3-14 against the skin by fingers. At this time, the injection needle 3-11 penetrates vertically into the subcutaneous tissue of the user because it has an "L" shape. Accordingly, the user can carry out the penetration of the injection needle 3-11 instantaneously without any observation with the naked eye. Therefore, the user feels little pain upon penetrating the injection needle 3-11 into the subcutaneous tissue. By virtue of such a configuration of the injection needle unit 3, the automatic insulin syringe device can be conveniently used, as shown in FIG. 13. Since the injection needle 3-11 penetrates vertically into the subcutaneous tissue of the user by virtue of its "L" shape, there is no phenomenon that the injection needle 3-11 is blocked at its tip by the subcutaneous tissue of the user. Thus, the injection of insulin is smoothly carried out. Accordingly, the feeding tube can have a reduced diameter and an increased length. Since the feeding tube 1 has a reduced diameter, it is possible to minimize the wastage of insulin occurring upon venting air existing in the feeding tube 1 and injection needle 3-11 and to reduce the manufacturing costs. Since the feeding tube 1 also has an increased length, it is possible to extend the range of the position of the injection needle 3-11 on the body of the user. Accordingly, it is possible to achieve convenience in use. Since the bacterial infection prevention member 3-14-1, which is made of a disinfected nonwoven fabric, is attached to the depressing member 3-14, it is possible to prevent the depressing member 3-14 from coming into direct contact with the skin of the user upon penetrating the injection needle unit 3 into the subcutaneous tissue. Accordingly, it is possible to prevent the user from being infected.
Since the injection needle 3-11 penetrates vertically into the subcutaneous tissue of the user by virtue of its "L" shape, as mentioned above, it hardly moves in the subcutaneous tissue even when an external force is applied thereto. Accordingly, there is no damage of the subcutaneous tissue. Of course, there is no phenomenon that the blood flows out of the subcutaneous tissue. The user also does not feel any pain.
In the case of the injection needle unit mentioned above, the needle protection cap 3-18 is used which has a configuration as shown in FIG. 14. The needle protection cap 3-18 has a needle tip receiving hole including a smaller diameter portion 3-18-1 with the same diameter as the injection needle 3-11 and a larger diameter portion 3-18-2 with a diameter larger than the diameter of the injection needle 3-11. Since the needle protection cap 3-18 has such a configuration, there is a problem in that it is difficult to separate the needle protection cap 3-18 from the injection needle 3-11 because of the small diameter of the diameter portion 3-18-1. As a result, the injection needle 3-11 may be damaged. Since the smaller diameter portion 3-18-1 has a small diameter, a capillarity phenomenon may occur between the inner surface of the needle protection cap 3-18 and the outer surface of the injection needle 3-11 when the liquid medicine is outwardly discharged from the injection needle 3-11 to vent air existing in the feeding tube 1 and injection needle 3-11. In this case, a part of the discharged liquid medicine is absorbed in the bacterial infection prevention member 3-14-1, thereby causing the user to be uncomfortable. The injection needle 3-11 has a sharp bent portion 3-11-1 between the vertical and horizontal portions thereof due to its "L"-shaped structure. This sharp bent portion 3-11-1 of the injection needle 3-11 may be subjected to excessive stress when the user moves excessively during injection. For instance, when the needle tip of the injection needle 3-11 moves from a position indicated by the solid line of FIG. 15 to a position indicated by the phantom line of FIG. 15 as the user exercises or conducts hard work, or due to other reasons, the sharp bent portion 3-11-1 of the injection needle 3-11 may be subjected to excessive stress. In this case, the injection needle 3-11 may be broken. For this reason, the reliability of the above mentioned injection needle unit is degraded.